Traditionally, displays present information in two dimensions. Images displayed by such displays are planar images that lack depth information. Because people observe the world in three-dimensions, there have been efforts to provide displays that can display objects in three-dimensions. For example, stereo displays convey depth information by displaying offset images that are displayed separately to the left and right eye. When an observer views these planar images they are combined in the brain to give a perception of depth. However, such systems are complex and require increased resolution and processor computation power to provide a realistic perception of the displayed objects.
Multi-component displays including multiple display screens in a stacked arrangement have been developed to display real depth. Each display screen may display its own image to provide visual depth due to the physical displacement of the display screens. For example, multi-display systems are disclosed in U.S. Patent Publication Nos. 2015/0323805 and 2016/0012630, the disclosures of which are both hereby incorporated herein by reference.
When first and second displays or display layers are conventionally stacked on each other in a multi-display system, moire interference occurs. The moire interference is caused by interactions between the color filters within the layers when projected onto a viewer's retina. For example, when green color filters overlap, light is transmitted making for a comparative bright patch. When a green filter is over say a red filter, not as much light will be transmitted making for a dark region. Since the rear and front displays or display layers have slightly different sizes when projected onto the retina, the pixels will slowly change from being in phase to out of phase. This has the effect of producing dark and bright bands otherwise known as moire interference.
Certain example embodiments of the instant invention provide solution(s) that make moiré interference in MLD systems vanish or substantially vanish, but without significantly sacrificing the rear display resolution and contrast. In certain example embodiments of this invention, the MLD system includes first and second displays. A refractive beam mapper (RBM) may be utilized in order to reduce or eliminate moire interference.
In example embodiments of this invention, there is provided a display device comprising: a first display in a first plane for displaying a first image; a second display in a second plane for displaying a second image, wherein said first and second planes are approximately parallel to each other; and a beam mapping element (e.g., refractive beam mapper) located between the first and second displays and comprising a plurality of microlenses configured to direct incident rays from the second display in a pseudo random manner through sub-pixels of the first display and toward a viewer.
A refractive beam mapper may or may not be used in combination with other techniques for reducing moire interference (e.g., color filter offset or dissimilar color filter patterns on the respective displays, diffuser techniques, and/or subpixel compression) in various embodiments of this invention.